NAS corresponds to the highest stratum of a control plane between user equipment (UE) and a network node (e.g. mobility management entity (MME)) in a wireless communication system. NAS protocols include protocols for mobility management (NN) and session management (SM) between the UE and MME. For example, evolved packet system (EPS) MMM (EMM) protocol can provide procedures for controlling UE mobility and security of NAS protocols. EPS SM (ESM) protocol can include a procedure of processing EPS bearer context and can be used for bearer control provided by an access stratum (AS) and user plane bearer control.